Hydraulic jack



April 11, 1950 A. A. MILLER 2,503,347

HYDRAULIC JACK Filed Sept. 12, 1945 v 5 Sheets-Sheet 1 xIIIIIIIIIIIIIIII mm 15221227? ErZZiz/r ZZ/frezi [UV/Er April 11, 1950 I'A. A. MILLER I HYDRAULIC JACK Filed Sept. 12-, 1945 3 Sheets-Shget 2-April 1950 A. A. MILLER I 2,503,347

HYDRAULIC JACK Filed Sept. 12, 1945 I 3 Sheets-Sheet 3 Patented Apr. 111950 [TED EPAT DFFIZLCE HYDRAULIC JACK Arthur Alfred. Miller,-Mcltllenry; 111;, assignor to Miller" Rroducts a copartnership'consisting of Arthur Alfred'iMiller and Thou? (Jharles: CasanovApplication September 12, 1945, Serial No. 615,785

6(Claimsl2 (Cl. 254-422) The present invention-pertains toWeight raising"devices and moreparticularly'toan improved and efiicient type of ahydraulic jack wl'iicl ii is adapted to be manually" operated andreleased through the medium of a; hydraulic control to effect theraising and lowering'ofa load supportinghea'd. The jackheadis supportedby a novel arrangement of-pivota-lly connected'lazy tongs links andstabilizing links, having hydraulically actuated operating blocksmounted intermediate the ends of selected upper and' lower-lazy tongslinks to provide pivotal connections for the remaining lazy "tongs linksand alsoproviding free ends forthe attachment'of 'the stabilizing links.

An object of theinventiondsthe provision of'a weightlifting device ofsimple and effective construction, including a: hydraulically operatedlifting unit involving novelly" assembled" lazytongs links andstabilizing" links," whereby the"- objects and features contemplated areobtainable with economy and facility.

It is an' object ofthe invention to provide an improved andsimplifiedform of jack wherein the lazy tongs'lifting unit is adapted to'be'operated by a hydraulic piston mechanism-which is convenientlypositioned to "facilitate convenient operation thereof to'eifect bothraising and lowering of the lift'ing unit.

Another object of the invention is the provision of a'lazy tongs'typeofjack provided with I hydraulic operating meansincluding a manuallyoperable crank connection whereby the hydraulic operating" means maybe'operated to raise'the lifting'unit' and 'wherein the hydraulicoperating means'may be conveniently released toeifect a gradual andsteady lowering of the lifting unit.

It is furthermore an object'of' this invention to provide a scissorstype'jack'operable'by hydraulic means, thelifting and loweringoperations of which are effected through the rotation and shifting of a:manually operated crank shaft control.

A furtherobject of the invention is the provision of a scissors or" lazytongstype of lifting jack wherein crank operated hydraulic pumpmechanisms are operable'for raising the jaclt and wherein lowering'ofthejack is conveniently ef fected by the operationof a release means.

It'is an important object of this invention to provide a scissors-typeof lifting jack operable I by hydraulic means, the operation; of which.is governed by r the manual rotation and; shifting of a control medium,therotation'of whicha'causes raising. of the jack: whilezshiftingthereof permits retraction and gradualilowering of thetjack: 55

Another objectofthe invention is the provision of a hydraulic scissorstypeof jack mechanism provided with a reinforced lifting head or saddlehaving side plates for enclosing portions of" the lazy tongs memberstoserveas a shield therefor in either a-raisedor-'lowered position of thejack mechanism.

A further feature of 'theinvention is the pro'-' vision of a hydraulictype of scissorsjack wherein a-manuall'y operable crank handle isadapted to be removablyengaged with a' couplingunitfor eitherrotating-or shifting acrank mechanism to cause operation of the jack toeither raise or lower the same through the control of the direction'offl'ow of a liquid medium.

Another object of the invention is to provide a scissors typeof liftingjack operable by'hydraulicmeans wherein thepumping and release ofliquid" for actuating the jack is governed by a manually operable crankshaft type of control which may be either rotated or shifted to respectively cause raising or lowering of the jack through th'e'control of afluid medium.

Another object of th'e'invention is theprovision ofa hydraulic'scissorsjack wherein piston operated' control blocks and stabilizing links arepivotally, connected between the endsofupper and lower lazytongsim'embers' tothe outerfree ends 'of which the stabilizing linksarealso connected..

It is an important object" of" this invention to provide i an improvedand simplified form'of a hydraulic operated scissors. jack wherein theoperationi-of lazy-tongs mechanisms are stabilized by a novel connectionfor stabilizing means andfa positioning of hydraulicallycontrollediactuating connections intermediate the ends. of twooppositely positioned members of the l'azyiton'gs mech anisms, .wherebytheobjects sought are adapted tobe realized .with economy and facility. I

Qther and; further important objects and features ofthis invention willbe apparent from the-disclosures in the specification and'theaccompanying drawingsi Onflthe drawings:

Figure iris aiside elevational view of scissors typeihydraulic jackillustrated in. collapsed. form and embodying=.th'e.iprinciples of thisinvention;

EigureZlis a sectionaliviewof the hydraulic operating. mechanismtaken onsubstantiallyline IIr-II of Figure V1, with parts shown inielev'ationand;withtparts= omitted and including a. drive coupling for connecting acrank handle with. a crank shaft of. thehyd'raulic mechanism;

Figure -3-is -alongitudinal central vertical section of the scissorsjack in a partly raised position, and including a sectional view of thehydraulic control mechanism, with parts shown in elevation;

Figure 4 is an enlarged sectional view of the lower portion of thehydraulic control mechanism taken on line IVIV of Figure 3 with partsshown in elevation;

Figure 5 is a fragmentary sectional view of the lower right-hand portionof the hydraulic control mechanism with the coupling unit partly shownin section showing the hydraulic crank shaft control pulled outwardly bymeans of the operating crank handle to open the release valvecontrolling the discharge of the hydraulic liquid 1 medium out of thepiston hack into the liquid reservoir to permit lowering of the jack;

Figure 6 is a fragmentary and elevational view of the upper portion ofthe jack to show the shape of the lifting head or saddle having shieldsor guard plates secured thereto to partially enclose the togglemechanism;

Figure 7 is a transverse sectional detail view taken on line VII--VII ofFigure 5; and

Figure 8 is a fragmentary longitudinal sectional view taken on lineVIII-VIII of Figure '7 with parts shown in elevation and with theoperating crank arm removed.

As shown on the drawings:

This invention relates to an improved and efficient type of ahydraulically operated lifting or raising jack adaptable for use inconnection with the raising of automobiles, heavy trucks or for use inconnection with the lifting or raising of other heavy devices or objectsto hold the same in a raised position and act as a temporary supporttherefor. The improved jack mechanism is of the scissors or lazy tongstype wherein the lazy tongs unit is adapted to be conveniently raisedand lowered by a manually operable hydraulic unit which governs theoperation of a piston member connected for actuating the lazy tongs tocause either raising or lowering thereof depending upon the flow of thehydraulic medium into or out of the piston cylinder. The jack isfurthermore adapted for raising or lowering a load of any selectedweight at a speed depending upon the rate of rotation of a manuallyoperable crank handle connected for operating the hydraulic control.

A novel feature of the present hydraulic jack is the mounting of ahydraulic unit in an inclined position to permit a crank handle to bereadily attached and disposed in an inclined position so that the outeroperating end thereof may be conveniently rotated to facilitate raisingof the jack head or cradle and furthermore permitting convenient releaseof the hydraulic medium to permit gradual lowering of the jack head orcradle without making it necessary for an operator to stoop and crawlinto inaccessible places to either position, operate or release thejack.

A novel feature of the present hydraulic jack is contained in the lazytongs structure which has the operating blocks thereof mounted betweenthe ends of pairs of toggle members to permit projectin ends of saidmembers to be free for the reception of selected ends of equalizinglinks leaving the opposite ends of said equalizing links free to bepivotally connected intermediate the ends of the respective togglemembers to which the operating blocks are secured.

The improved hydraulic scissors type jack herein disclosed comprises abottom or base plate I having two spaced pairs of apertured bearing lugs2 and 3 integrally formed thereon for respectively supporting bearingshafts 4 and 5, the outer ends of which are reduced in diameter to formsuitable supports for the lower ends of members forming parts of acollapsible and expendable type of Weight lifting and lowering mechanismof the lazy tongs type.

The load lifting and lowering mechanism is supported on the base plate Iand is of the scissors type including two oppositely positioned sets oflazy tongs or toggle frame members comprising a pair of lower lazy tongslinks or toggle members 6 which have the lower ends thereof pivotallysupported on the reduced ends of the base bearing shaft 4. A second pairof lower lazy tongs links or toggle members 7 have the lower endsthereof pivotally supported on the reduced ends of the base bearingshaft 5. The toggle members 6 and I on each side of the jack cross oneanother and project upwardly and outwardly in opposite directions asillustrated in Figure 3.

Pivotally connected by means of a pivot stud 8 to each of the lowertoggle members I, at a point a short distance from the shaft 5, is thelower end of a lower stabilizing link 9, the upper end of which ispivotally engaged on a pivot stud l0 carried in the lower projecting endof an upper lazy tongs link or toggle member H, two of which areprovided. The upper ends of the two lazy tongs links or toggle membersII are pivotally supported on the reduced ends of an upper shaft l2which projects through apertures in two spaced looped or U-shapedflanges i3 spaced from an intermediate or middle reinforcing flange I4.The spaced flanges l3 and I4 form an integral part of a jack liftinghead or saddle l5. The lifting head I5 is constructed of a sheet metalplate having portions thereof folded upon itself to provide thedownwardly projecting flanges l3 and 14 as illustrated in Figure 6.

Each of the upper lazy tongs links or toggle members I I has a pivotstud 16 supported thereon a short distance inwardly from the upper endthereof. Pivotally supported on the stud i6 is the upper end of an upperstabilizing link H, the lower end of which is pivotally supported on apivot stud I8 carried by the upper projecting end of one of the lowerlazy tongs links or toggle members I. It will thus be noted that thelower and upper sets of stabilizing links 9 and H are mounted so thatone end is pivotally connected intermediate the ends of either one orthe other of the toggle members 1 or II while the other ends of saidstabilizing links are pivotally connected to projecting ends of therespective toggle members I or I l as clearly illustrated in Figure 1.

Also supported in the depending flanges E3 of the jack head I5 isanother upper shaft l9, positioned opposite and parallel to the uppershaft I2 on the jack head. Pivotally engaged on the outer reduced endsof the upper shaft I9 are the upper ends of a pair of upper lazy tongslinks or toggle members 20 which extend downwardly and cross on theinside of the upper toggle members II. The lower ends of the two uppertoggle members 20 are pivotally engaged on trunnions or gudgeons 2|which are integrally formed on opposite ends of a lower toggle operatingblock 22. The trunnions 2! of the lower toggle operating block 22 arerotatably engaged in openings provided near the upper ends of the lowertoggle members I a short distance inwardly from the studs 18 as shown inFigure 1, thereby pro- 55; viding an arrangement in which the-lower:ends of the upper stabilizing-links Iiiaren'sonnected to the upperprojecting; ends-of the =lower toggle membersnl' beyond the=-point ofsupport for: the lowerrtoggle operating block 22.

'I he lower toggle operating block 22 is recessed to: receive aretaining wedge unit 2131 hich ispassaged-i to 1 register with: atransverse opening inatheblock 2-2 to rec'ei-ve the outer end of a.

hydraulicallyoperated piston rod on plunger; 24% 10' securely loohedtherein; The outer: end portion: of the piston rod 24iscircumferentially grooved at 25*? to: receive an; internal ringforming: an. integral part of the wedge-unit z, which is of a splitlnconstruction to facilitate engagement thereof around the grooved end ofthe/piston'irodi 2's: as: illustrated in'Figure 3:

The scissors or: togglemechanisms for: a-ctue ating: the jack headincludes an: upper-a toggleoperating: block 2'6 which' is' formed with:integral 2O outwardly projecting end 1 trunnions or: gudgeons 2-7; Thetrunnions' 2 1 are rotatablyengaged in: openings provided in the lowerportions! of the upper togglemembers I lsat a short distanceinwardly-from the studs lilliwhich: are supported in: the lowerprojecting ends. of. the togglemem. hers H to serve as supports for, theupper ends. of'the lower stabilizing links-9 as showndn Figure 1i Itwillthus be-notedthatthe-jack: head. iS'is adapted to be'operatedby lazytongs or the r scissors type'arranged in two groups or: sets on oppositesides of the jack head and including: upper and lower sets ofstabilizing linksconnccted to projecting ends of the togglememberszfiand.

l i and to-points'between the supporting-ends of said toggle members andthe points..where\-- the supporting trunnions of the lazytongsaoperating blocks engage through the toggle imemberss'li and; Hi

Theupper toggle operating block.261-is-trans-v 4O versely recessed andis welded or otherwise rigidly secured around the exterior of a.hydraulic cylinder -28 'Which. is mounted: in a an inclined: po. sitionand slidably'receives theupper endofrthe piston rod 24. The piston rod;2143 isaalso' supported in an inclined position as illustrated-tinFigure .1 3 and projects through-suitable packing: in a closure -cap29=which is.:tightly.-threadedfion: the lowerexteriorly threaded end of thecylinder ze toinsure'a tight'joint. Rigidly secured ion the inner orupper end of the pistonrrod 21!: isaanpis ten 30" which is adapted. tobeoperated by a: hydraulic operating fluid; such: as oil; water or anyother: suitablefluid adaptablefor useas a liquid medium for actuatingthe. piston andithei piston rod to cause operation.ofztheitogglemechanisms tov raise the jack. head.

The hydraulic. cylinder. 281 projects 1ongi--- tudinally and centrallythrough-lthe upper portion of ahydrauli-c housing or jacket3il e and istightly sealedin collars- 32'. and 33 which areintegrally formed onopposite ends of! the upper central portions of 1 the end walls of thehousing 3!. The upper end of the cylinder: 28 projects through thehousing sleeve 33 andzis' exteriorly same ha-s'beenemptied.

threaded to receive a'closure. cap 34:.toseal the upper. end of thecylinder.

The hydraulic housing'3l is provided with a. chamber 35 which isfilledwith a-hydraulic opacrating liquid such as oil which forms ajacketvaround the cylinder 28 where it projects through. the housing.

Normally thejacl: head [5 is inits=lowermost position as illustrated-inFigure i, so that the hydraulic piston rod-2'4 is:-in'-itsoutlermostposition=-with1 the pistom 30%:1'n tne lower: end of: the

cylinder 28 sothat substantially all of the'op'en=- ating 'fluid isdischarged i from the-lower sideof? the piston 303 outwardly through a--combination:

fluid feed and discharge-pipe36, the outer end? of which is connected bya pipe'coupl-ing Biwhich is engaged in a sleeve 38 integrallyformedi onthe lower central portion: of one-end of the hydraulic housing 3 Tightlyconnected-- to the inner endof the pipe coupling 3 is one:- end of afluid pipe 39 which is disposed within the fluid chamber 35 and'hasthe=sec0nd end thereof'pro jecting into a'valve housing wiwhich -is*integrally formed or cast in a lower corner of the fluid housing 3!'-and is disposed.at right anglestha fluid-pump cylinder 4|; Thefluidpumpcylinder: l! is integrally connected by-means of a web fl" toasecondpump cylinderfi43; onee end ofiwhich is-integr-ally connected at ri'ght-angles to a second valve 1 housing A l: which -is also integrallyformedin one ofthe cornersofi the housingdl in align ment with the valvehousing 48 and spaced therefrom as-shown-in Figured. I

llhe valve housing 40' is provided- Withe -liquid receiving" chamberid-which opens through one end ofthe housing 3 I andis -closed bya-threaded plug 46. Seated against the inner end of the closure plug 15is one end 0? a valvecontrol spring t1, the innerend -of which seatsagainst a ball valve l8 to' normally. hold the same seated in a valveseat d9 formed in the valve housing llii Alsoseated against thebal1'valve-48-"' is'-oneend of a control spring 59 which-is disposed'within a passage or chamber in the valve housing4E3 and communicateswith the inner' end of the pump chamber within the cylinder-41 The second endof the control spring fi'il engagesaga-insta second intakeballvalve 51 to normally holdthe same seated against anauxiliary valve seat52 to normally close'a fluid intake passage-or port 53 provided in theinner end of the-valve housing 49- as clearly-illustrated in Figure-4;

In a similar manner the second valve housing; M; in the. housing 31,is--provided witha fli'iid' chamber 54 the outer end of 'which opensthroughan openingin an end wall of the housing 3 I and is closed; bymeanszofxa threa'ded' closure-"plug 55 i Engagedi against the inner endof. the closure plug 55 is; one end' of: a: maint control-t spring. 5'65which-:issdisposedin the chamber 523 andihasssthec opposite end?thereof. engaged iagainst azmain.iballi:v valve: 5'!- which 1 is adaptedto: be normallyaheld; seated againsttai mainu valve: seat: 5&1- to;close-1 off .i the chamber; 54 from the chamber-y at the innerx end. of:the chamber Ell-of the pump cylinder.- 43'. Disposed within'; the.chambers at the. end. 2 of the pump chamber 59 i-is an. auxiliarycontroluspring; 6&3. one endlof which seats against. aflmain: ball.valve 51 while. the-rather. end seats. against an. auxiliary balLvalve.61 to. hold thesame against an auxiliary valve seat 62' for controllinga,fillii.

intake passage orport 63; provided. in the inner end of the valvehousing 44 to permit fluid to be suctioned through the passage '63" tofill the pump chamber 59* to refill the same after the" To permit theoperating fluid to be pumped from the chamber 54'- into tliechamber- 45' and theninto the outlet pipe-3 9 a'connecting or-trans fer pipe fidisprovided with one end of-"said'pipe being connected 'tothe-'valve'housing M to com municate withthe chamber 54 therein whilethe other end' of said pipe 63- is= connected to the valve housingine-to communicate with' thee-chain berl 45i' therein';

For the purpose of insuring the steady pumping of a fluid from the fluidchamber 35 of the housing 3|, two alternately operating pump mechanismsare provided including the pump cylinders 4| and 43 hereinbeforedescribed. Slidably mounted in the pump chamber 64 of the pump cylinder4| is a pump piston stem or rod 65 which projects out of one end of thecylinder 4| and has rigidly secured on the projecting end thereof a pumphead 66 having engaged around the inner side thereof one end of a coiledspring 61, the inner end of which engages around a portion of the pumpcylinder 4| and seats in a recess provided in a plate 68 having openingstherein to permit the plate to be engaged around the pump cylinders 4|and 43 as illustrated in Figure 4. Slidably engaged in the chamber 59 ofthe pump cylinder 43 is a pump piston stem or rod 69, the outer end ofwhich projects from the pump cylinder and has rigidly secured thereon apiston head 19. Engaged around the projecting end of the pump cylinder43 is a coiled spring 1|, one end of which seats against the inner sideof the piston head 10 while the other end seats in a recess provided inthe plate 68.

The two pump piston units are alternately operable to alternately drawthe pumping fluid from the chamber 35 through the intake ports 53 and 63into the respective pump chambers 64 and 59 when the pump piston rodsmove outwardly in their respective cylinders by the action of the pistoncontrol springs 6'! and II, one of which is compressed when the other isexpanded as shown in Figure 4. The piston control springs jointly act tohold the piston heads 66 and 19 in contact with a double cruciform typeof crank shaft unit comprising a crank shaft 15 journaled in suitablebearings provided on the housing 3| and extending outwardly from theinterior of the housing 3| through a packing unit 12.

Rigidly formed on the crank shaft 15 within the chamber 35 are twospaced diametric double cranks l3 and 14 which form an integral part ofthe crank shaft 15 and are disposed at right angles with respect to oneanother so that the crank 13 is positioned to coact with the piston head66 while the crank 14 coacts with the piston head 10 when the crankshaft is rotated to cause alternate operation of the twin pumps. Thecrank shaft 15 slidably projects through the packing unit 12 and isnormally held in its innermost position by means of a coiled controlspring 16 which is coiled around the crank shaft within the chamber 35of the housing 3| with one end of said spring being engaged against aflat portion of the packing unit 12 while the inner end of said springseats against a control disk 11 which is rigidly secured on the crankshaft 15 adjacent the crank 74 as illustrated in Figure 4.

The crank shaft 15 which drives the twin pump mechanisms for pumping thehydraulic fluid into the lower end of the hydraulic cylinder 28 to causeoperation of the jack is adapted to be manually rotated. For the purposeof rotating the crank shaft I the outer projecting end thereof has acoupling head I8 attached thereto by means of a sleeve 19 which issecured to the crank shaft 15 by means of a set screw 80 or othersuitable fastening means. Rigidly secured longitudinally within thecoupling head 18 are two diametrically opposite and parallel stop pins8|. The coupling head is chambered and has the outer end thereof closedby means of a wall which is provided with a central opening 82 and witha diametric slot 83 which crosses the opening 82 as clearly illustratedin Figure '7.

For the purpose of rotating the crank shaft 15, a removable crank handle84 is provided, the outer end of which is shaped with a crank extensionand a hand grip (not shown) of the ordinary type to permit rotation ofthe crank handle 84. The driving or attachment end of the crank handle84 is provided with a diametrically positioned driving pin 85, as shownin Figure 5, and said pin is adapted to be projected through thediametric slot 83 as the end of the crank handle 84 is projected throughthe central opening 82 of the coupling head 18.

When the crank handle 84 is rotated, the driving pin 85 will engagebehind the pins 8| in the coupling head to cause rotation of thecoupling and the crank shaft 15 together with the cranks 13 and 14. Thecranks "I3 and 14 coact with the respective piston heads 66 and 10 tocause alternate operation of the pump piston rods 65 and 69 whereby thefluid in the chamber 35 of the hydraulic housing 3| is alternately drawnthrough the ports 53 and 63 to be pumped into the respective chambers 45and 54 and then through the pipe 39 to enter the hydraulic cylinder 28below the piston 30 to gradually move the same upwardly in the cylinder28. The piston 30 draws the piston rod 24 inwardly to cause the toggleoperating block 22 to be drawn toward the toggle block 28 therebycausing operation of the toggle members as well as the stabilizing linksto gradually and evenly raise the jack head l5 to a desired height.

After the operating piston 30 has been moved upwardly in the hydrauliccylinder 28 by the pumping of the hydraulic fluid into the lower chamberof said cylinder, the raised jack head I5 will stay in its elevatedposition until the fluid below the piston 30 is released and ispermitted to gradually flow outwardly through the pipe 36 and thenthrough the pipe 39 into the chamber 45 of the valve housing 40 andthrough the connecting pipe 63 into the chamber 54 of the valve housing44.

In order to permit the hydraulic fluid to escape from the chamber 54 ofthe valve housing 44, a fluid release mechanism is mounted within thefluid chamber 35 of the housing 3| and is supported in an interiorlythreaded sleeve or collar 86 which is integrally formed on the valvehousing 44 as clearly illustrated in Figures 2 and 4. The fluid releasemechanism includes a valve block 81 having an externally threaded stem88 integrally formed on one end thereof and threaded into the sleeve 86to communicate with the chamber 54 in the valve housing 44. A releaseball valve 89 is engaged in the valve block 81 and is normally heldseated in a closed position against a valve seat 90 by means of a coiledspring 9|, one end of which seats against the ball valve 89 while theother end is engaged against a transverse diametric pin 92 in thethreaded stem of the valve block 81 as illustrated in Figure 4.

The release valve block 81 is provided with a discharge chamber orpassage 93 with which diametrically opposed discharge openings or ports94 communicate to permit the discharged fluid to pass back into thechamber 35 of the housing 3| as shown in Figure 4. Slidably mounted in apassage provided in the valve block 81 is a discharge valve control pinor stem 95 which projects into the chamber 93 against the ball valve 89.One end of the control pin 95 projects from the block 81 into contactwith a cam 96.

forming :a part of avalvecontrolfingerwr arm 19'! which is pivotally=-supported onla ;pivot pin 98. The pm 198 'is mounted :between :a pair:of plates 99 secured 'i'Ol'l wopp'osite =-sides of :the valve :block:8! and projecting beyond one :end :thereof to :provide a' space ifor:the controlw-cam 96 to rotateiin. Rotation of-ithecam Stir-causesoperation of the control pin=555 and thereleaseball valve Bil-when thecontrol finger'Blis swung outwardly from the fulllineiposition:illustrated ine'Figure'A by the outward movement ofithecontrol disk "H.

' Outward movement of the controldiskfl 1' occurs when the crank shaft15 iis slidablyfmoved outwardly against the action of 'the 30011811-spring I6 when aipull is fmanuall-y :exerted fonthez'crank handle 'il lcausing the pins-:85 to-engage against the end wall of thecouplingih'ead fistopullthe coupling head 1 and the crank shaft -75 fromthe positions illustrated in'EigureZ into the positions illustrated inFigure in which the spring "i6 is compressed and in which-the disk Tl:swings or rocks the control finger 9? from the position shown in Figure4 into the-operating :position shown in Figure :5. The cam 95 thus actson the control pin 95 and causes the ball valve 88 to'move into its openposition thereby-{permitting the fluid Whichis being forced=out of thelower .end of the hydraulicvcylin'der 2-3-tobe discharged throughthe-chamber '93 and the discharge port 94 backinto-the chamber 35-:ofthe housing-3| for reuse.

When the crank shaft "is ipulledioutwardly to causeopening of the.release-valvei89, the return i of the control fluid *backrinto thechamber permits "a-gradual 'even lowerin'g of the jack head '55 from araised position into-1a lower position during which time thehead'raising :lazy tongs mechanism and thestabilizing links asso ciatedtherewith are adapted vto be gradually moved back into their normalrcollapsed-positions, as illustrated in Figure 1,-to-permit the jackmechanism to be removed :from beneath .an tob- J'e'ct after beinglowered.

For the purpose of gaining admittance -:to the mechanisms :mountedwithin thehydraulic housing 3-l said housing .is provided with .anopening which is tightly closed by means-of a removable closure sealplate 1.0! secured-to-the housing by means of screws "or other suitablefastening means.

Referring to Figure 6, -a zp-rotectingguard :is provided for thescissors jack, and this guard consists :of a pair-of-sid'e plates-orhood sections use, the upper ends of which are bent'over to engagebeneath the side "margins of the jack head R5 to which the upper flangesof the side plates are rigidly secured. Theguard plates I02 serve toprotect the lazy tongs mechanisms and also afford a safety means.toiprotect the lazy tongs mechanisms by preventing anything fromgetting between "the"members of'lazy tongs operating mechanisms toprevent proper operation thereof. The guardplates i 02 have been omittedfrom tall of the figures except "Figure Binorder to :more clearlydisclose the various mechanisms of the-scissors jack. -It will, ofcourse, beunderstood that the guard plates maybe omitted when not neededor said guard plates may .form -an integral .part of the jack hea'd2115.

The improved "hydraulic jack is admirably adapted for raising light oriheavy loads, which after being raised maybe-gradually and uniformlylowered at a constant rate by the release "of %the fluid control valveunit, ithe opening of which is controlled by the shifting or slidable)movement of the crank i-tshaft 1:5. When the shaft This rotatediby'meansof the crankhandl-e 84, the fluid pump mechanisms areactuatedto cause the :fiuid to be pumped into the hydraulic L5 cylinder2-8 to move the pistoniheadtfi upwardly in said cylinder to actuate thetoggle-members sand the stabilizing links of the llazy -tongs unit tocause *raising of the jack head M to any desired-height withinthelimitsifor which thejack 10 is designed.

-Itwi11 thusbe noted that an important feature -of the hydraulicrjack'is the provisionof a hy- -\dr-aulic control unit comprising acrank shaft which -is rotatable --for causing pumping .of the 115 fluidtoicause operation of the-piston rodito raise the jack head. Thecrankshaft is furthermore longitudinally:shiftable by exerting anoutward pull-on-the crank shaft against the actioniof the controlspringtocause cam o-peration of the re- :20 lease ball valve to permitrelease of the sum from the-hydrauliccylinder and aigradualeeven.lowering'of the iackhead and the toggleimechanisms supporting the same.

While :an improved type of hydraulic control 125 unit-is associated withthe lazy tongs or scissors jack unit, it will of course be .understoodthat the'hydraulically operated piston mechanism may be replaced by anoperating screw, the rotation of which maybe accomplished by .adirectcon- 39 nection thereto of a suitable' crank handle or by imeansiof areduction gear unit and :an auxiliary crank handle drive such vas theoperating drive unit illustrated in imy copen'ding application wfor-,patent for a Scissors jack, filed-June 21, 1945, '35 U. S. -SerialNo.-.600,'763.

:Another important feature of the present invention is the :provision ofa lazy tongssjack "unit wherein the toggle members .are -mounted for*raising and lowering the jack ahead, said itogg'le 40 members beingarranged with the actuating blocks mounted off center or between theends 'of selected pairs ;of the toggle members while the-stabilizinglinks-areeachmounted with one endiconnected to a ,projecting end of oneof the toggle members on which the actuating blocks are supportedwhile-the other end of thestabiliz- .ing A link is 5 pivotally connectedanother o'fzsaid block supporting toggle members at a-pointiintor-mediate the ends thereof.

It will furthermore be understood that various other details ofconstruction -may be varied through a wide range without departing fromthe principles of this invention, and it is, therefore, not the purposeto limit-the :patent granted 55 "hereon otherwise than necessitated bythe scope .of the appended claims.

-I claimasmy invention:

Alazy tongs I-jack device comprisinga base, :a jack head, a pair-oflower lazy tongs vmembers pivotally connected to thesbase apair of upperlazy tongs :members pivotally connected to .the

j a'ck head, an operating block connected to ione Y of thelower:'1azyton-gs 'membersintermediate the ends thereof and pivotally connected toone end of one of the upper lazy tongs members a-second block connectedto-thesecondupperlazy tongs .member intermediate the-endsthereofiand toone rend-of the second lower lazy tongs member, "a

"driven member co-ac-tin with .said blocks, =.driving means foroperating the driven member -to move the blocks toward one-another-toactuate the lazy tongs members-to raise the jackheads release:mechanism, and an 0peratin'g :means ifor =only 'Pshifting the driving:means to cause the same to operate the :release mechanism toicause 11'separation of the blocks and gradual lowering of the lower and upperlazy tongs members to lower the jack head.

2. A lazy tongs jack device comprising a base,

a jack head, a pair of lower lazy tongs members pivotally connected tothe base, a pair of upper lazy tongs members pivotally connected to thejack head, an operating block connected to one of the lower lazy tongsmembers intermediate the ends thereof and to one end of one of the upperlazy tongs members, an upper stabilizing link connected to one end ofthe lower lazy tongs members to which the block is connected and havingthe other end connected to the second of said upper lazy tongs membersintermediate the ends thereof, a second operating block connected to thesecond of said upper lazy tongs members between the ends thereof and toone end of the second of said lower lazy tongs members, a lowerstabilizing link having one end connected to one end of th second ofsaid upper lazy tongs members and the other end pivotally connectedbetween the ends of the first of said lower lazy tongs members, a drivenmember supported by the blocks, a driving means for actuating the drivenmember to move the blocks toward one another to cause raising of th jackhead,

and a release mechanism operable by the driving means to cause loweringof the jack head.

3. A lazy tongs jack device comprising a base, a jack head, a pair oflower lazy tongs members pivotally connected to the base, a pair ofupper lazy tongs members pivotally connected to the jack head, anoperating block connected to one of the lower lazy tongs membersintermediate the ends thereof and to one end of one of the upper lazytongs members, an upp Stabilizing link connected to one end of the lowerlazy tongs members to which the block is connected and having the otherend connected to the second of said upper lazy tongs membersintermediate the ends thereof, a second operating block connected to thesecond of said upper lazy tongs members between the ends thereof and toone end of the second of said lower lazy tongs members, a lowerstabilizing link having one end connected to one end of the second ofsaid upper lazy tongs members and the other end pivotally connectedbetween the ends of the first of said lower tongs members, a drivenmember supported by the member to operate the hydraulic means, and a Qhydraulic release mechanism operable to cause release of the hydraulicmeans and lowering of the jack head when the control handle is actuatedto shift the shaft member into engagement with the release mechanism.

4. A lazy tongs jack device comprising a jack head. a base, crossedtoggle members connecting the head and base, operating blocks connectedto opposite pairs of the toggle members between the ends thereof,stabilizing links having one end of each thereof connected to an end ofone of the toggle members and the other end connected intermediate theends of an opposite toggle member, hydraulic means for operating theblocks to cause raising of the jack head, a crank shaft, operating meansfor rotating the crank shaft to cause operation of the hydraulic meansand elevation of the jack head, a hydraulic release mechanism connectedwith the hydraulic means, and a control carried on the crank shaft 12for operating the hydraulic release mechanism to cause lowering of thejack head when the crank shaft is shifted by the operating means.

5. A hydraulic jack mechanism comprising crossed toggle members, a jackhead supported thereon, guards carried thereby, a block member supportedon two of said toggle members intermediate the ends thereof, a pistonrod connected with said block member, a piston on said rod, a hydrauliccylinder enclosing the piston, a second block member on the hydrauliccylinder and connected to two other toggle members intermediate the endsthereof, a fluid housing connected to the hydraulic cylinder, pipeconnections between the hydraulic cylinder and the fluid housing aplurality of fluid pump mechanisms in the housing, a fluid intake andoutlet valve for each of the pump mechanisms, a fluid release valve unitin the housing, a control shaft rotatably and shiftably mounted in thehousing, crank members on the control shaft for alternately operatingthe pump mechanisms to cause fluid to be pumped into the hydrauliccylinder to operate the piston and piston rod to cause movement of saidblock members toward one another to raise the jack head, a control diskmounted on the control shaft within the housing, a spring on saidcontrol shaft engaging said control disk to hold the control shaft inits innermost position to position the cranks in operating engagementwith the pump mechanisms, a coupling unit connected with a projectingend of the control shaft, and a crank handle removably engaged in thecoupling unit and adapted to be rotated to cause rotation of the controlshaft and the crank members to pump fluid into the hydraulic cylinder toactuate the piston and piston rod to raise the jack head, said crankhandle adapted to be pulled to shift the control shaft against theaction of the spring to cause the control disk to operate the releasevalve mechanism to permit return of the fluid from the hydrauliccylinder back into the fluid housin and permit gradual lowering of thejack head.

6. In a scissors type jack including a base, a lifting head, crossedlazy tongs members supporting the head on the base, operating meansconnected with diagonally opposite upper and lower lazy tongs membersintermediate the ends thereof and leaving one projecting end of each ofsaid selected lazy tongs members free, and stabilizing links pivotallyconnected to the free projecting ends of said selected lazy tongsmembers and to points intermediate the ends of said selected lazy tongsmembers.

ARTHUR ALFRED MILLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,135,440 Cremieu-Javal Apr. 13,1915 1,723,131 Burkholder et al. Aug. 6, 1929 1,736,202 Larson Nov. 19,1929 1,859,830 Kummel May 24, 1932 1,954,558 Conrad Apr. 10, 19342,097,032 Marlowe Oct. 26, 1937 2,176,636 Meacham Oct. 17, 1939 FOREIGNPATENTS Number Country Date 667,423 France June 17, 1929 732.613 FranceDec. 28, 1932

